Speed of the Brushed DC motors can be varied by changing the operating voltage or the strength of the magnetic field. Depending on the connections of the field to the power supply, the speed and torque characteristics of a brushed motor can be altered to provide steady speed or speed inversely proportional to the mechanical load. The electrical noise generated by a DC motor falls into two categories electromagnetic interference (RF interference) and the electrical noise generated on the power rail. This paper deals with the techniques to reduce the noise reduction of Brushed DC motor. The RF interference can couple into other portions of the circuit and cause circuit malfunction and performance degradation. The motor induced RF noise can significantly decrease the usable RF range. Reduction in the level of RF interference, motors should be placed as far away from sensitive circuits as physically possible. Motor’s metal casing typically provides enough shielding capability for reducing the over-the-air RF interference, but an extra metal enclosure should provide much better RF interference reduction capability. To reduce the level of RF interference, motors should be placed as far away from sensitive circuits as physically possible, for more reduction extra metal enclosure should also be provided. We also found that for suppressing RF interference in case of common mode interference, simple LC low pass filter is incorporated. Elimination of other electrical noises is also done by attaching motor with simple speed controller. Higher order LC filters can further improve the noise-filtering performance.
